This is a competitive renewal for the University of Washington Alzheimer's Disease Patient Registry (ADPR). The ADPR is a model clinical and epidemiologic database for dementia and Alzheimer's disease (AD). It was established in late 1986 by a grant from the National Institute on Aging and is based in a large health maintenance organization -- Group Health Cooperative of Puget Sound (OHC).The ADPR has been enrolling only those cases of dementia and AD who have come to medical attention since 1 January 1987; providing each of the potential cases with a standardized, physical neurological, and neuropsychological examination leading to a criteria-based diagnosis. The goals of this application are to first continue the model ADPR as in previous grant periods so that additional cases can be enrolled, allowing ongoing epidemiologic/genetic studies to proceed and making future investigations feasible. And second, to begin a major new initiative: formation of a population-based cohort(free of dementia) and to follow the cohort forward in time. From the cohort we will eventually be able to compare the occurrence of dementia (primarily AD and vascular dementia) between this study and cross-cultural studies. The specific aims of the project are: To continue a 7-year old model Alzheimer's Disease Patient Registry which includes: case finding, enrollment and diagnosis of incident dementia cases from the population base of Group Health Cooperative (as in the previous grant cycles), and to provide additional incident cases of AD for case control studies of risk factors, diagnostic markers and genetic studies as well as for potential clinical trials; 2. To follow all dementia cases enrolled in the ADPR monitoring annual change in baseline cognitive/ behavioral tests and medical history, ultimately obtaining cause of death and neuropathologic diagnosis of dementia: a) to assess factors associated with survival in AD and other dementia cases (utilizing the statistical techniques of analysis); b.) to describe the association tween clinical and neuropathologic diagnosis; c.) to describe the natural history of AD from first diagnosis to death; 3. To assemble a cohort of non-demented elderly subjects from the same population base as the previous ADPR population and to screen them every two years to detect and diagnose new dementia cases (following the protocol established in cross-cultural studies of Japanese persons conducted in Seattle, Hawaii, Japan and of Chinese persons in Taiwan): a) to allow cross-cultural comparison of dementia (AD, MID) incidence rates and risk factors by continued follow-up of the cohort into subsequent grant periods; b) to collect data necessary to evaluate new potential risk factors such as neurotoxic exposures and pharmacologic histories.